Why does getFieldState work withe useFieldArray, is it because the field array is not an actuall field.

[Felixmurithi]

I dont understand why getFieldState is not able to pin down wether a field in a useFieldArray hook is dirty and I have to write more code to get that

[initial-d]

Yes, that is basically the reason: the field array name itself is not the same thing as an individual registered input field.

useFieldArray({ name: 'items' }) manages the array structure, but the actual registered fields are usually paths like:

items.0.name
items.0.price
items.1.name

So getFieldState('items') is not usually the right way to ask "is any row in this array dirty?". It is better for a concrete field path:

const state = getFieldState('items.${index}.name', formState)
console.log(state.isDirty)

For array-level dirty state, use formState.dirtyFields or useFormState and inspect the array branch:

const { control } = useForm({
  defaultValues: {
    items: [{ name: '' }],
  },
})

const { dirtyFields } = useFormState({
  control,
  name: 'items',
})

const isAnyItemDirty = !!dirtyFields.items

A couple of important details:

• Dirty tracking needs complete defaultValues; otherwise RHF has nothing reliable to compare against.
• If you need per-row dirty state, inspect dirtyFields.items?.[index] or call getFieldState for the concrete field paths inside that row.
• Be careful if you identify rows only by index, because append/remove/swap can move indexes. Use the field.id from useFieldArray for React keys, and use indexes only for RHF field names.

So the short version is: getFieldState works best for actual registered leaf fields. For a field array as a whole, read the corresponding branch of dirtyFields or subscribe with useFormState({ name: 'items' }).